Individual cylinders of an internal combustion engine may include at least one cylinder head and at least one cylinder block. The cylinder block may comprise a number of cylinder bores equal to a number of pistons arranged in the cylinders. The pistons may be guided through the bores in an oscillating motion, the pistons combined with cylinder walls may form combustion chambers of the internal combustion engine.
The cylinder head comprise one or more valves configured to adjust charge exchange. During the charge exchange, the discharge of the combustion gases via the exhaust-gas discharge system may take place via at least one outlet opening, and a feed of fresh air via an intake system may take place via at least one inlet opening of the cylinder. Parts of the intake system and/or of the exhaust-gas discharge system may be integrated in the cylinder head.
Thermal loading of the internal combustion engine may be maintained within a desired operating range via a cooling arrangement arranged within spaces of the internal combustion engine. The cooling arrangement may be a liquid or air type cooling arrangement. Herein, the present disclosure may specifically refer to a liquid-type cooling arrangement, however, it will be appreciated by those of ordinary skill in the art that the disclosure may additionally apply to an air-type cooling arrangement.
In some examples, the cooling arrangement may be arranged as a coolant jacket adjacent to cylinder walls of the combustion chamber. The heat may be dissipated to the coolant, which may be water, optionally mixed with additives, present in the coolant jacket of the cylinder head or block. The coolant may be conveyed, such that it circulates, via a pump which may arranged in the cooling circuit and which may be mechanically driven via a traction mechanism drive. The heat dissipated to the coolant is discharged from the interior of the cylinder head or block in this way, and may be extracted from the coolant again in a heat exchanger. A ventilation vessel provided in the cooling circuit may function for ventilating the coolant or the circuit.
Air may enter the cooling circuit from the outside. For example, air may undesirably enter the cooling circuit during a filling of the cooling circuit with coolant or admixing of additives to lower the freezing point of the coolant, which may be performed to allow the internal combustion engine to be more suitable for winter operation. Air may however also ingress in the case of unsealed cooling circuits, for example in the case of porous coolant hoses. Air in the coolant circuit may degrade the engine due to air bubbles forming in the coolant pump, resulting in the coolant pump pumping air and not coolant. By doing this, the coolant may no longer be sufficiently cooled and the internal combustion engine may be thermally overloaded (e.g., operating at a temperature greater than the desired temperature range).
Additionally, air may not absorb heat as well as liquid coolant and may form a barrier between the coolant and coolant jacket surfaces, mitigating heat transfer from the cylinder head and/or block to the coolant jacket. The barrier of air may create localized maxima and/or hotspots, which may also lead to degradation (e.g., cracking).
For the above-described reasons, a ventilation system, such as a degas bottle, may be arranged in the cooling arrangement to remove air trapped in the cooling circuit along with coolant vapor bubbles formed therein. The ventilation system may be strategically arranged such that conditions of the coolant circuit may self-regulate coolant flow therethrough, wherein the self-regulation may be temperature based.
The ventilation system may be arranged at a geodetically highest point of the cooling arrangement, whereby the discharge of air and vapor bubbles may occur via buoyant forces that act on the gas bubbles and drive the gases situated in the circuit upward and through the ventilation system. The coolant jackets, coolant ducts and/or hoses may, in the arranged position of the internal combustion engine, rise in the direction of the ventilation system, such that the bubbles are led to the ventilation system.
According to the previous examples, a ventilation system, such as the system described above, may be generally arranged on and fastened to a bulkhead, which delimits the engine bay with respect to the passenger compartment, at a distance from the internal combustion engine. This arrangement of the ventilation system demands long coolant hoses, in particular a long ventilation line leading to the ventilation system and a long return line that branches off from the ventilation system. Furthermore, a desired volume of coolant increases, and a weight of the engine cooling arrangement increases with the greater coolant volume. The greater coolant volume also demands a longer warm-up process after a cold start of the internal combustion engine compared to coolant systems with less coolant, which may be decrease fuel economy and increase emissions.
Long coolant hoses or long coolant lines may be associated with bends and curves of said hoses or lines, and furthermore with a low gradient, that is to say a small ascent per unit distance. The latter in particular may decrease ventilation and promote formation of flow dead zones. The costs of the engine cooling arrangement as a whole may increase. Said another way, a greater buoyant force is demanded to act on the gas bubbles when the hoses are longer.
In one example, the issues described above may be addressed by a liquid-cooled internal combustion engine having at least one cylinder head comprising at least one cylinder, an intake system for the supply of air, which intake system comprises an inlet manifold, said inlet manifold laterally adjoining the at least one cylinder head and comprising a plenum chamber, from which at least one cylinder-specific intake line branches off for each cylinder, and a liquid-type cooling arrangement which, to form a cooling circuit, is equipped with a pump for conveying the coolant and with a ventilation vessel, the ventilation vessel being incorporated into the cooling circuit of the internal combustion engine by means of a ventilation line and a return line, and where internal combustion engine further comprises where the ventilation vessel is arranged above the inlet manifold and between the inlet manifold and the at least one cylinder head, a virtual connecting line between the inlet manifold and the at least one cylinder head intersecting the ventilation vessel. In this way, the compact arrangement of the ventilation vessel may decrease a desired volume of coolant, decrease manufacturing costs, and increase fuel economy.
As one example, the ventilation vessel is arranged in a close-coupled position, specifically above the inlet manifold, between the inlet manifold and the cylinder head. Here, a virtual line that connects the inlet manifold and the cylinder head to one another may intersect the ventilation vessel. The arrangement according to the disclosure of the ventilation vessel may provide a compact design and dense packaging of the drive unit as a whole in the engine bay. The length of the coolant hoses may be reduced relative to the previous examples described above where the ventilation vessel is fastened to the bulkhead. In particular, the ventilation line leading to the vessel and the return line branching off from the vessel may be shortened. In this way, the desired coolant quantity, and with this the weight of the engine cooling arrangement, can be reduced.
The reduced coolant quantity may ensure an accelerated warm-up process during a cold start of the internal combustion engine, and thus a reduction in the friction losses of the internal combustion engine, and decreased emissions during the cold-start.
Shorter coolant hoses or shorter coolant lines may comprise fewer bends and curves. In some cases, the arrangement according to the disclosure of the ventilation vessel may comprise lines integrated into the internal combustion engine, for example into the cylinder head. Additionally or alternatively, external hoses may be omitted from the ventilation vessel. The susceptibility of the engine cooling arrangement to leaks may thereby be decreased. Additionally, the formation or hot spots or local maxima may be mitigated due to the shorter coolant hoses comprising fewer twists and/or bends.
Furthermore, the arrangement according to the disclosure of the ventilation vessel may lead to higher gradients in the cooling circuit, that is to say steeper gradients, whereby ventilation of the engine cooling arrangement may be assisted and/or promoted. Said another way, buoyant forces needed to act on the gas bubbles to remove gas from the coolant arranged in the coolant circuit may be less than the buoyant forces needed in the previous examples described above where the hoses are longer. Furthermore, the costs for the engine cooling arrangement can be reduced.
Embodiments of the liquid-cooled internal combustion engine may comprise where a supercharging arrangement or supercharging device is provided.
Supercharging may increase power in which the air demanded for the combustion process in the engine is compressed, as a result of which a greater charge air mass may be provided to each cylinder in each working cycle. In this way, the fuel mass and therefore the mean pressure can be increased.
Supercharging may increase a power output of an internal combustion engine while maintaining an unchanged swept volume, or for reducing the swept volume while maintaining the same power. At any rate, supercharging may lead to an increase in volumetric power output and a more expedient power-to-weight ratio. If the swept volume is reduced, it is possible, given the same vehicle boundary conditions, to shift the load collective toward higher loads, at which the specific fuel consumption is lower. Supercharging of an internal combustion engine may minimize fuel consumption, that is to say it may increase the efficiency of the internal combustion engine.
In some embodiments, the transmission configuration may provide downspeeding, whereby a lower specific fuel consumption is likewise achieved. In the case of downspeeding, use is made of the fact that the specific fuel consumption at low engine speeds is generally lower, in particular in the presence of relatively high loads.
A supercharged internal combustion engine may be thermally more highly loaded, owing to the increased mean pressure compared to a naturally aspirated engine, and therefore may increase demands on the cooling arrangement, and as a result, supercharged internal combustion engines may desire a liquid-type cooling arrangement.
Here, embodiments of the liquid-cooled internal combustion engine may comprise where the supercharging of the internal combustion engine, at least one exhaust-gas turbocharger is provided in which a compressor and a turbine are arranged on the same shaft.
In an exhaust-gas turbocharger, a compressor and a turbine are arranged on the same shaft. The hot exhaust-gas flow may be fed to and expand in the turbine with a release of energy, as a result of which the shaft is set in rotation. The energy supplied by the exhaust-gas flow to the shaft is used for driving the compressor which is likewise arranged on the shaft. The compressor delivers and compresses the charge air supplied to it, as a result of which supercharging of the at least one cylinder is obtained. A charge-air cooler may be arranged in the intake system downstream of the compressor, where charge-air cooler cools the compressed charge air before it enters the at least one cylinder. The cooler lowers the temperature and thereby increases the density of the charge air, such that the cooler also contributes to improved charging of the cylinders, that is to say to a greater air mass. In effect, compression by cooling may be obtained.
The difference between an exhaust-gas turbocharger in relation to a supercharger, which can be driven by means of an auxiliary drive, consists in that an exhaust-gas turbocharger utilizes the exhaust-gas energy of the hot exhaust gases, whereas a supercharger draws the energy demanded for driving it directly or indirectly from the internal combustion engine and thus adversely affects, that is to say reduces, the efficiency, at least for as long as the drive energy does not originate from an energy recovery source.
If the supercharger is not one that can be driven by means of an electric machine, that is to say electrically, a mechanical or kinematic connection for power transmission may be desired between the supercharger and the internal combustion engine.
A difference between a supercharger and an exhaust-gas turbocharger consists in that the supercharger may generate a demanded boost pressure a greater range of engine conditions, specifically regardless of the operating state of the internal combustion engine, in particular regardless of the present rotational speed of the crankshaft. This applies in particular to a supercharger which can be driven electrically by means of an electric machine.
Embodiments of the liquid-cooled internal combustion engine may comprise at least one supercharger which can be driven via an auxiliary drive.
Embodiments of the liquid-cooled internal combustion engine may comprise an exhaust manifold of the exhaust-gas discharge system integrated into the at least one cylinder head.
As a result of the merging of the exhaust lines within the cylinder head, the overall length of the exhaust lines may decrease, and the line volume of the exhaust manifold is reduced. The merging of the exhaust lines within the cylinder head may allow dense packaging of the drive unit.
Benefits may be achieved in the case of exhaust-gas turbocharging because the turbine can be arranged in a close-coupled position, whereby the exhaust-gas enthalpy of the hot exhaust gases, which may be based on the exhaust-gas pressure and the exhaust-gas temperature, may be utilized optimally, and a fast response behavior of the turbine or of the turbocharger may be more likely. Furthermore, the path of the hot exhaust gases to the different exhaust-gas aftertreatment systems may be short, whereby an exhaust gas temperature may remain relatively unaffected and the exhaust-gas aftertreatment systems reach their operating temperature or light-off temperature quickly, in particular after a cold start of the internal combustion engine.
An internal combustion engine with an integrated exhaust manifold may be subject to high thermal load and may desire the liquid-type cooling arrangement described above.
Embodiments of the liquid-cooled internal combustion engine may comprise where the ventilation vessel is formed at least partially integrally with the inlet manifold.
In particular, embodiments of the liquid-cooled internal combustion engine may comprise where the ventilation vessel is formed in one piece with the inlet manifold.
A ventilation vessel formed at least partially integrally with the inlet manifold may comprise a smaller space demand, which may decrease packaging constraints.
The integral form of the ventilation vessel with the inlet manifold may eliminate the need for other or further fastenings of the ventilation vessel. Thus, manufacturing costs may decrease and manufacturing efficiency may increase, thereby improving manufacturing practices.
Embodiments of the liquid-cooled internal combustion engine may comprise where the ventilation vessel is formed at least partially integrally with a valve cover of the at least one cylinder head. The valve cover may serve as a cover for valve drives arranged in the cylinder head. In some examples, the valve cover is a cam cover.
In some examples, a valve cover, already present on an internal combustion engine, may form at least a portion of the ventilation vessel.
The valve cover may be a plastic part shaped by injection molding into the intake manifold and may be present prior to manufacture of the ventilation vessel. As such, the ventilation vessel may be integrated and/or incorporated into the already present valve cover. Additionally or alternatively, the ventilation vessel may be molded into the intake manifold, separately from the valve cover.
Embodiments of the liquid-cooled internal combustion engine may comprise where the ventilation line is at least partially integrated into the at least one cylinder head.
Embodiments of the liquid-cooled internal combustion engine may comprise where the return line is at least partially integrated into the at least one cylinder head.
The integration of a line into the cylinder head at least partially, or in sections, possibly entirely, eliminates the demand for an external hose. Furthermore, the susceptibility of the line to degrade (e.g., form a crack and/or leak) may decrease.
Embodiments of the liquid-cooled internal combustion engine may comprise where the return line connects the ventilation vessel to the pump.
Embodiments of the liquid-cooled internal combustion engine may comprise where the ventilation vessel is manufactured from plastic. Plastic may comprise a low specific weight, wherein the relatively low thermal load capacity may provide a desired stability and thermal communication therethrough. Good moldability and degrees of freedom with regard to shaping may be additional benefits.
Embodiments of the liquid-cooled internal combustion engine may comprise where the pump may be an electrically operated pump, which is supplied with power for example from an on-board battery, and which can convey coolant even when the internal combustion engine is deactivated. The electrically operated pump may adjust both the coolant pressure and the coolant throughput as desired. Additionally or alternatively, the pump may be a mechanically operated pump and/or traction operated pump. The traction operated pump may be operated by a camshaft of the internal combustion engine via arranging the pump adjacent to the cylinder head or in the cylinder head, and thus also adjacent to the ventilation vessel. A traction mechanism may include a belt, wherein the belt may be a low-friction belt. In some examples, the pump may be fastened at the inlet side to the at least one cylinder head.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
FIGS. 2 and 3 are shown approximately to scale.